True West is about the sibling rivalry between two estranged brothers who have reconnected. The play begins with brothers, Austin and Lee, sitting in their mother's house. This is the first time they've seen one another in five years. The two are not on good terms, but Austin attempts to appease his older brother, who is more dominant. We learn that their mother is on vacation in Alaska and that Austin is house sitting. Austin is trying to work on his screenplay but Lee continually distracts him with nonsense questions. The two brothers seem on edge with one another. When Austin suggests that Lee leave, Lee threatens to steal things from the neighborhood. Austin calms him down and the night ends with the two of them on neutral terms.
Lee talks about the security level of their mother’s house, and how Lee went into the desert to find their dad. Austin then tells Lee to leave the house because a film producer, Saul, is coming by to look at Austin’s screenplay about a “period piece”. Lee agrees to leave in exchange for Austin's car keys. Austin is reluctant at first but eventually relents and Lee promises that he will have it back by six. Lee departs.
Saul and Austin are discussing their agreement when Lee enters with a stolen television set. Saul and Lee discuss golf and make plans to play the next day, excluding Austin because he doesn't play, despite his desire that Lee have nothing to do with Saul.
Lee proposes a script idea to Saul and Saul reacts positively. Austin begins writing Lee’s story out loud, but stops, saying it doesn't resemble real life. The two brothers fight and eventually Austin asks Lee for his car keys back. Lee assumes Austin is trying to make him leave, and Lee says he can’t be kicked out. Austin says he wouldn't kick him out because he’s his brother. Lee counters that being brothers means nothing because in-family murders are most common. Austin assures him they won't be driven to murder over a movie script. The two admit to being jealous of each other’s lives, Lee kindly returns the car keys and the scene closes with Austin typing Lee’s story.
Lee returns from his golf game with Saul. He tells Austin that Saul has promised him an advance for his story idea outline that Austin wrote. They celebrate until Lee informs Austin that he expects Austin to write the screenplay. Austin questions this knowing he has his own work, but Lee continues to inform him that Saul has chosen to drop Austin's screenplay. Austin warns Lee that he needs to be careful with messing within this line of work and that he has a lot at stake on his own project. The scene ends with Austin threatening to leave and go to the desert as Lee tries to calm him down.
Austin confronts Saul about his decision to buy Lee’s screenplay. He argues that Saul only offered to buy the screenplay because he lost a bet. Saul wants Austin to write both his and Lee’s story but Austin refuses. Austin thinks that Lee’s story is illegitimate and not relevant to the time period. Due to Austin’s rejection to the job, Saul decides to drop Austin’s story and to find a different writer for Lee’s story. The scene ends with Saul making plans for lunch with Lee.
Austin is drunk and annoying Lee, who is now the one trying to concentrate on a screenplay. Lee makes a bet with Austin and Austin appears to be going crazy. Austin resolves to leave the house and they continue to bicker about Lee's ability as a screenwriter. Lee finally asks for Austin's help writing the script and starts drinking with him.
Austin is polishing toasters that he stole while Lee is smashing a typewriter early in the morning. The two continue to do this while they are carrying on a conversation. Austin is proud of what he has done. Lee wants to see a woman, but Austin refuses because he is married. Lee throws a fit while on the phone with the operator because he cannot find a pen to write down what the operator is saying. Austin begs Lee to go to the desert with him because he thinks there is nothing for him where he is. The brothers make a deal that Austin will write the play for Lee if Lee takes him to the desert.
In the final scene, the house is ransacked and Lee and Austin are working vigorously on their script. Their mother returns and Lee is first to notice her. She is confused by her sons' appearances and the state of her house. Austin tells her that he and Lee are going to take off into the desert, but Lee says they might have to postpone the trip because he doesn't think Austin is cut out for the desert life-style. Austin responds by attempting to strangle Lee and their mother storms out of the house in disarray. Austin finally lets go of Lee, and is worried for a second that he’s killed his brother. As Austin moves for the door, Lee rises. The two brothers face one another as the lights fade.